The present invention relates to irrigants and disinfectants for surfaces and, more specifically, irrigants and disinfectants used for dental and medical procedures and situations.
Dentists, dental surgeons and dental hygienists and their patients are well aware of the importance of meticulously sterilizing and disinfecting dental instruments. Indeed, since dental instruments are used directly in a patient's mouth, sometimes for invasive or surgical procedures, it is of paramount importance to minimize the presence of microorganisms carried by dental instruments. The microorganisms can range from relatively harmless bacteria to dangerous pathogens. Consequently, efforts are deployed to remove microorganisms from dental instruments and from the fresh water lines feeding dental instruments such as air/water syringes, high speed turbines, and ultrasonic scalers, or from saliva evacuation lines.
Sodium hypochlorite is universally used as an antiseptic for root canal irrigation, its principal functions in root canal treatment being microbicidal, dissolving organic material, and lubrication. However, a disadvantage of sodium hypochlorite is that it is highly toxic to human tissues and cells in concentrated form and corrosive and potentially dangerous to humans at the concentrations at which it is at its most effective as an irrigating medium. Consequently, solutions having low concentrations of sodium hypochlorite are generally used, which results in using larger quantities of solution than what would be considered ideal quantities of the solution.
Similarly, solutions tend to lose their useful properties over time. The additives and agents that compose these solutions tend to oxidize rather quickly once they are subjected to normal environments and surroundings, which causes the strengths of solutions to deteriorate over time and to lose activity. While this deterioration is not necessarily detrimental for everyday household cleaning and disinfecting, it is more pertinent when working with and around skin and tissue. Nonetheless, more stable compounds and solutions are still useful in all situations.
Biofilms
Adhesion to surfaces is a common and well-known behavior of micro-organisms in many habitats, specifically habitats where water or other fluids may be present. This adhesion and the subsequent microbial growth lead to the formation of biofilms. Bacterial biofilms promote increased biomass deposition, resulting in surfaces and environments that are less than desirous regarding sterility and cleanliness.
Treatment of biofilms arises in many different environments and on many differing environments, including treatment of water supplies, treatment of medical and dental equipment, treatment during medical and dental procedures, and general cleaning and disinfecting of a wide range of surfaces. Even though there is a wide range of areas for which treatment may be necessary or desirous, there are also some common factors to take into account. Treatment compounds and solutions must not be too corrosive for their intended uses. For example, you would not use an overly strong solution, as this may etch and damage a surface, or cause pain and injury if used during medical or dental procedures. Thus, it is necessary to provide solutions that are strong enough to treat biofilms without causing irreversible damage.
There have been several ways discussed to treat biofilms, such as processes using halogen and oxygen based compounds, including hypochlorite, chlorite, chlorate, and peroxygen compounds, to treat biofilms. However, especially when treating biofilms related to people and internal surfaces, such as on the dentin of teeth during procedures like root canals, care must be taken so that the treatment process is not dangerous to an individual. Furthermore, treatment of a mature biofilm is often unsuccessful because the biocides only react with the outer layers of the biofilm and tend not to sufficiently treat the entire surface areas, external and internal, leaving a healthy and substantial bacterial community on the surface of the substrate, which rapidly regrows. Bacteria within biofilms also develop increasing resistance to biocides on repeated dosing. It has been found that biocides further induce cross-resistance to other biocides.
A range of bactericidal substances, commonly termed biocides, germicides, or microbicides, are available, all of which are claimed by their producers to quantitatively to kill bacteria occurring in aqueous systems. Biocides target a range of cellular loci, from the cytoplasmic membrane to respiratory functions, enzymes and the genetic material. However, different bacteria react differently to bactericides, either due to inherent differences such as unique cell envelope composition and non-susceptible proteins, or to the development of resistance, either by adaptation or by genetic exchange. Bactericides should therefore be evaluated against the organisms which they are chosen to control, i.e. the dominant ones in the system to be treated. The composition of microbial populations in systems varies with the environment, and changes considerably after treatment with various biocides by selection for resistant strains. Bacteria growing as biofilms are also significantly more resistant to most of the currently known antimicrobial agents, as compared to planktonic bacteria, posing ongoing challenges for methods for their control.
In treatment for medical and dental situations, a few solutions have been developed that are currently used. Examples of compounds commonly used in medical treatments include quaternary ammonium compounds, parachlorometaxylenol compounds, gluteraldehyde compounds, phenolic compounds, such as chlorophenols, phenols, and thymol, peroxyacetic aced, alcohols, chlorine dioxide, chloroxyenols, tetracyclines, iodine, cresols, caprylic acid, formaldehyde, and trichlorosan compounds. While useful, there are still drawbacks. These compounds can have adverse side effects and possible negative impacts if used too often or in too great of concentrations. Other examples include highly corrosive materials, such as sodium hypochlorite, calcium hypochlorite, or other hypochlorite or hypohalogen compounds. Consequently, only small amounts of these materials can be safely used on and around humans. However, these compounds also tend to oxidize rather quickly, which reduces the efficacy of these compounds over time. Once these compounds are opened and come into contact with the air, the shelf life for these products is relatively short due to decomposition of the compounds. To correct for this shortcoming, the strength of these compounds ideally would be high. However, as stated above, it is not possible to make the products too strong, or they could do severe damage to a patient.
The prior art does not adequately provide a stable agent that maintains acceptable stability after storage times and storage conditions typical of actual usage conditions encountered in the real world. For instance, most commercial product distribution channels result in products aging several months following manufacture before being placed on sale, followed by significant delays before actually being used. During this time, products are seldom stored under ideal conditions, but rather are exposed to temperature variations typical of the home, field and industrial environment.
Many typical commercially sold bleach products containing hypochlorite solutions have a half-life of around six months or less. This stability is generally sufficient for everyday household cleaning chores and duties. In medical and dental situations better stability is desired, especially when other compounds are added to the hypochlorite solutions. When wetting agents, surfactants, penetrating agents, and/or other similar additives and active agents are added to the hypochlorite solutions, stability and efficacy is lost due to oxidation of the agents.
Other treatment solutions and detergent compositions in the medical and dental field are known in the art. Chlorhexidine based compounds are one class of compounds used in biocide solutions and antimicrobial solutions.
Chlorhexidine is used to prevent and treat the redness, swelling, and bleeding of the gums associated with gingivitis. It is classified as a biguanide antimicrobial drug. Chlorhexidine is generally accepted to be effective as an antiseptic hand wash for methicillin-resistant Staphylococcus aureus (MRSA). Chlorhexidine is obviously an easily tolerated and effective antiseptic for the daily practice of medicine and surgery. Its oral use is also well documented (e.g. in ill subjects who cannot brush their teeth adequately). However, the teeth discolorations that are caused by the drug are disturbing.
Chlorhexidine is an antiseptic agent effective against plaque, oral flora including Candida sp. and Candida albicans, and is used as a cleanser for surgical scrub, skin wounds, germicidal hand rinse, and as an antibacterial dental rinse. Chlorhexidine is active against gram-positive and gram-negative organisms, facultative anaerobes, aerobes, and yeast. Chlorhexidine is essentially nontoxic when applied to the skin or mucous membranes, compared with disinfectants including cresol, bleaching powder, and phenol which are, in general, toxic to cells of the body. Other common antiseptic agents include benzalkonium chloride, cetrimide, hexachlorophene, iodine compounds, mercury compounds (i.e. thimerosal), alcohol and hydrogen peroxide, hexamine hippurate, triclosan, cetylpyridinium chloride, and dequalinium. Other substances which can be used for antiseptic purpose include boric acid and volatile oils such as methyl salicylate and some botanical essential oils.
Hexachlorophene and benzalkonium chloride are used primarily in hand or face washes. Benzalkonium chloride must not be applied to areas which have not been fully rinsed as it is inactivated by organic compounds. Benzalkonium application may include disinfecting instruments and preserving drugs in low concentration form. Aqueous iodine solutions are less effective than alcoholic solutions, but the drying effect of the alcoholic component can be irritating to abraided skin. Povidone iodine is convenient to use as it is less irritating, but not as effective.
Chlorhexidine is also used as a safe antiseptic or disinfectant application to prevent body infection and in oral rinses for treating sore gums, mouth ulcers, periodontal and endodontic infections, and preventing plaque on teeth. It is used in the form of acetate, gluconate or hydrochloride, either alone or in combination with other compounds, such as cetrimide. However, these chlorhexidine compounds have a tendency to gel or coagulate when agents, such as surfactants, wetting agents, leveling agents, penetrating agents and the like, are added to the compounds. To prevent clotting or gelling, processes, which may include intricate steps, are carried out so that the compound has a suitable and useful equilibrium. However, in forming a stable solution or compound some of the efficacy of the system may be lost.
Thus, it would be advantageous to develop compounds and systems for medical, dental, and general cleaning solutions that have increased stability without overly affecting the efficacy of the solution.